Yarn trimmer for circular knitting machines



Jan. 11, 1966 G. w. WILSON 3,228,213

YARN TRIMMER FOR CIRCULAR KNITTING MACHINES Filed March 8, 1963 2Sheets-Sheet l nnumun WW1mmIii 50 FIG. 2

Q H :s f" *1 94 92 86 92 8O 84 24 \\ill\lillllllllII G as Q 84 m N 80 BYATTORN EYS Jan. 11, 1966 G. w. WILSON YARN TRIMMER FOR CIRCULAR KNITTINGMACHINES 2 Sheets-Sheet 2 Filed March 8, 1965 INVENTOR. GRADY W. WILSONMWYMA'MCMM Fl G. 6

ATTORNEYS United States Patent 3,228,213 YARN TRIMMER FOR CIRCULARKNITTING MACHINES Grady W. Wilson, Cayey, Inerto Rico, assignor toGordonshire Knitting Mills, Inc., Cayey, Puerto Rico, a

corporation of Pnerto Rico Filed Mar. 8, 1963, Ser. No. 263,767 7Claims. (Cl. 66-145) This invention relates to automatic yarn trimmingmechanism for use in a circular knitting machine having one or moreyarn-feeding stations. When in a knitting operation a yarn is introducedor taken out, a loose end is left which must be trimmed off before thearticle is ready for sale. In the past this has usually been done byhand. More recently mechanisms have been devised for trimming the yarnends automatically by mechanism incorporated in the knitting machine. Itis an object of the invention to provide yarn-clipping and yarn-handlingapparatus in a circular knitting machine equipped for yarn changing,which is simpler and more reliable than devices heretofore provided forthe same purposes. Other advantageous features will be recognized in thefollowing description of the invention and on the drawings, of whichFIGURE 1 is a perspective view of parts of a circular knitting machineon which an embodiment of the invention has been installed;

FIGURE 2 is a fragmentary perspective view from another angle and on alarger scale, of some of the mech anism shown in FIGURE 1;

FIGURE 3 is a section on the line 33 of FIGURE 1;

FIGURE 4 is an enlarged perspective view of the shear block shown inFIGURES l and 2;

FIGURE 5 is a plan view of the mechanism shown in FIGURE 1; and

FIGURE 6 is an enlarged fragmentary perspective view of parts shown inFIGURE 2.

The devices hereinafter described are shown on the drawings as attachedto a circular knitting machine of the type illustrated in Patent No.1,641,101, granted to Scott on August 30, 1927. The machine has acomplement of latch needles 24) arranged around a stationary disk 22which may be a dial cam cap, the needles being for convenience indicatedwithout heads in FIGURE 1. A ring 24 having teeth on its periphery isrotated in unison with the cylinder which carries the needles 20. Theteeth on the ring 24 are of the hand-saw variety with the cutting edgespreferably inclined forward in the direction of motion. The machine mayhave one or more yarn-feeding stations, one such station 26 beingindicated in FIGURE 1, two such stations 26, 28 being indicated inFIGURE 5. Each station may have several feeding fingers, two suchfingers 30, 32 being shown at the main station 26, two fingers 34, 36being shown at the auxiliary station 28. When a feeding finger at themain station, such as the finger 30, is lifted out of action, the lastneedle to take the yarn 38 therefrom carries it around the cylinder to ashear block 40 which is stationary and bears on a portion of the ring24. During this travel of the last needle to take the yarn, it drawsyarn from the elevated finger 30, the portion of the yarn 38 between thefinger and the needle being carried by the movement of the needle undera main yarn guide 42 which is mounted on the disk 22, against a verticalguide post 44, under an auxiliary yarn guide 46 and under an air block50. The air block 50, as shown in FIGURE 3, has a vertical bore 52therethrough. The lower end portion 54 of this bore is of smallerdiameter than the upper portion, a conical shoulder 56 being betweenthese portions. A ball 60 is seated on the shoulder 56, this ball havinga diameter less than that of the upper portion of the bore 52 so thatsuction created in the bore sufiicient to lift the ball draws air inthrough the orifice at the lower end of the bore. The block 50 ismounted on the disk 22 but part of the lower portion is cut away toprovide clearance 62 beneath the bore 52. When the idle yarn 38 is drawnpast the block 50 it is pulled under the block against a small guide pin64 in the clearance 62 which ensures that the yarn extends directlyunder the bore 52. The upper end of the bore is conveniently closed by ascrew plug 66. At certain periods during the operation of the machine,air under pressure is supplied to the block 50 from any suitable source(not shown) through a supply pipe 63 and a horizontal nozzle whichdirects the air stream across the upper part of the bore 52 into anexhaust pipe 72. The latter leads to a screened basket '74 in which hitsof yarn sucked into the bore 52 can be collected for disposal.

The jet of air across the bore 52 lowers the air pressure in the boreand the resulting suction lifts the ball 60 and draws air into the bore.If any loose yarn is in the clearance 62 beneath the block 50, it issucked up into the bore. When the air jet is shut off, the ball falls toits seat 56 and clamps any yarn or yarns which may then be extendingthrough the orifice at the lower end of the bore 52.

As the yarn 38 is carried around by a needle, the portion next to theneedle passes between two of the teeth of the ring 24. When this reachesthe shear block 40, the teeth pass under the forward cutting edge 76 ofthe block and the resulting shearing action severs the yarn at thatpoint, very close to the last needle to take the yarn. The free end ofthe idle yarn 38 is at once sucked into the bore 52.

The shear block 40 is illustrated in FIGURE 4. It consists of anelongated rectangular block of steel having a very hard inset 80 at theforward end of the bottom of the block. The lower front edge 76 of theinset 80 is the cutting edge which cooperates with the teeth of the ring24 to clip the yarns that are carried around by the teeth. The sides ofthis edge 76 preferably make an acute angle. The inset 80 is of veryhard material such as carbide steel or tungsten carbide. At the otherend of the block is another inset 84 of the same material as the inset80 to act as a wear piece. These insets result in long service by theshear block without resharpening or replacement. On the top surface ofthe block 49 is a central protuberance 86 on which presses a leaf spring88 an end of which is secured to the disk 22. Two headed screws 90 passloosely through the other end portion of the spring 88 and are threadedinto holes 92 in the top of the block 40, these holes being on oppositesides of the protuberance 86. The block is thus held loosely under thespring 88 which presses on the central protuberance. This floatingconnection allows the insets 82, S4 to press evenly on the ring 24.

A trigger for a stop-motion device is provided on the dial cam cap 22.This comprises two resilient leaf springs 94, 96 mounted on a block 98of insulation and connected to a wire 100 which leads to a source ofelectrical energy (not shown) which is grounded as usual. If a yarncarried around to the shear block 50 fails to be severed thereby and isdrawn in behind it, the yarn will press the leaf spring 94 into contactwith a grounded metal part of the machine, thus closing a circuit toenergize a stop-motion mechanism (not shown). If a needle becomes bent,it may catch on the shear block 40 and raise it so that one of thescrews 90 touches the spring 96 and closes the stop- 0 motion circuit.

I claim: 1. In a circular knitting machine having a circular series ofneedles and equipped for yarn changing, means for handling the yarnswhen changes are made, said means comprising a plate surrounded by saidneedles, a block mounted on said plate, said block having a verticalbore extending upward from the bottom thereof and a clearance between aportion of the bottom and said plate communicating with said bore, tubeconnections with the upper part of said bore for creating suctiontherein, the lower portion of said bore being of smaller diameter thanthe upper portion thereof, a ball in said upper portion having adiameter slightly larger than that of said lower portion of the bore andadapted to be raised by suction in the upper part of the bore, saidblock being arranged to receive thereunder yarns which are changed.

2. In a circular knitting machine, mechanism as described in claim 1,and yarn clipping means comprising a ring rotatable with said needles,said ring having outward projecting cutter teeth on its periphery, astationary shear block bearing on a portion of said ring over some ofsaid teeth, and a spring pressing said block resiliently on said ring.

3. In a circular knitting machine, mechanism as described in claim 2,said shear block having at its forward end a hardened blade elementbearing directly on said ring, said block having a floating attachmentto said spring.

4. In a circular knitting machine, mechanism as described in claim 3,said shear block having at its rear end a wear piece of the samematerial as said blade element.

5. In a circular knitting machine having yarn changing mechanism andmeans for cutting the yarns when changing, a block located between saidyarn changing mechanism and said cutting means with a clearance underpart of the bottom of the block to receive yarns which are beingchanged, said block having a vertical bore opening out at saidclearance, said bore having a short portion at its lower end of smallerdiameter than the upper portion of the bore the two portions having aconical seat between them, a ball having a diameter slightly less thanthat of the upper portion of the bore resting on said seat and adaptedto be raised by suction in the upper portion of the bore, and means forproducing suction in said bore above the ball.

6. In a circular knitting machine, yarn clipping means comprising arotatable ring having outwardly projecting teeth on its periphery, anelongated shear block with a cutting edge at one end bearing directly onsaid ring to cooperate with the teeth thereof, said block having acentral protuberance on the top surface thereof, and carrying thereon,between said protuberance and the respective ends of the block twoupstanding elements, and a leaf spring pressing on said protuberance,said spring having two holes through which said respective upstandingelements loosely extend.

'7. In a circular knitting machine, yarn clipping means as described inclaim 6, said shear block having at its forward end a hardened carbidesteel inset with a cutting edge bearing on said ring and at its rear enda carbide steel wear piece bearing on said ring.

References Cited by the Examiner UNITED STATES PATENTS Re. 25,584 5/1964Stack et a1. 66l40 2,579,773 12/1951 Williams 30350 2,884,775 5/1959Stack 66163 3,079,779 3/1963 Butler et al 6614O 3,083,553 4/1963 Moss etal 66-140 RUSSELL C. MADER, Primary Examiner.

DONALD W. PARKER, Examiner.

1. IN A CIRCULAR KNITTING MACHINE HAVING A CIRCULAR SERIES OF NEEDLESAND EQUIPPED FOR YARN CHANGING, MEANS FOR HANDLING THE YARNS WHENCHANGES ARE MADE, SAID MEANS COMPRISING A PLATE SURROUNDED BY SAIDNEEDLES, A BLOCK MOUNTED ON SAID PLATE, SAID BLOCK HAVING A VERTICALBORE EXTENDING UPWARD FROM THE BOTTOM THEREOF SAID A CLEARANCE BETWEEN APORTION OF THE BOTTOM AND SAID PLATE COMMUNICATING WITH SAID BORE, TUBECONNECTIONS WITH THE UPPER PART OF SAID BORE FOR CREATING SUCTIONTHEREIN, THE LOWER PORTION OF SAID BORE BEING A SMALLER DIAMETER THANTHE UPPER PORTION THEREOF, A BALL IN SAID UPPPER PORTION HAVING ADIAMETER SLIGHTLY LARGER THAN THAT OF SAID LOWER PORTION OF THE BORE ANDADAPTED TO BE RAISED BY SUCTION IN THE UPPER PART OF THE BORE, SAIDBLOCK BEING ARRANGED TO RECEIVE THEREUNDER YARNS WHICH ARE CHANGED.